Imagine you have a plugin called test and you loaded the plugin with

LOAD('plugin_test','index',ajax=True)

and the view should contain a link that reloads just the plugin (not the whole page). If you would add

bla bla
A("linktext",_href=URL(request.application,"plugin_test","index",vars=dict(delete=12345)) )
foo bar

this would reload the whole page, to solve this change it to

<div id="trg">
bla bla
DIV("linktext",_onclick="ajax('%s',[],'trg');"%URL(request.application,"plugin_test","index",vars=dict(delete=12345)) )
foo bar
</div>

now it should do what you want it to do (maybe you need to restyle the div to look like a link again)